Anode button for preventing leakage of x-radiation

ABSTRACT

A substantially hollow anode button formed for sealing in a glass wall of a cathode-ray tube envelope has a radiation shield positioned therein. The shield has a bottom and an upstanding circumferential wall which extends to a height just less than the interior height of the button. The shield is free to move within the cup to allow easy exit of cleaning or rinsing fluids used in tube processing.

United States Patent Edward C. Slick Warren;

Floyd ll. West, Sugar Grove, both of, Pa. Appl. No. 54,192

Filed July 13, 1970 Patented Aug. 17, 1971 Assignee Sylvania Electric Products Inc.

Inventors ANODE BUTTON FOR PREVENTING LEAKAG OF X-RADIATION 3 Claims, 2 Drawing Figs. [1.8. Ci 313/64, 174/5053, 250/108, 313/331, 315/85 Int. Cl G21f 3/00, i-lOlj 5132,1101 5/52 Field 0! Search 313/64, 356, 3111; 315/85; 250/108, 108 WS; 174/50.5,

[56] References Cited 7 uumzn STATES PATENTS 2,508,001 5/1950 Swedlund 1. 315/1 x 2,928,968 3/1960 Hoagland 313/64 FOREIGN PATENTS 294,446 4/1905 Netherlands 313/64 Primary Examiner- Roy Lake Assistant Examiner-V. Lafranchi AttorneysNorman J. O'Mailey, Donald R. Castle and 7 William H. McNeill ABSTRACT: A substantially hollow anode button formed for sealing in a glass wall of a cathode-ray tube envelope has a radiation shield positioned therein. The shield has a bottom and an upstanding circumferential wall which extends to a height just less than the interior height of the button. The

shield is free to move within the cup to allow easy exit of cleaning or rinsing fluids'used in tube processing.

PATENTEB AUG] 7 I97! INVENTORS. EDWARD c. SLICK &

FL D H. wesr iDcw Q M ATTORNEY ANODE BUTTON FOR PREVENTING LEAKAGE OF X- I RADIATION BACKGROUND OF THE INVENTION This invention relates to x-radiation shielding and more particularly to X-radiation shielding for anode buttons for use as a sealed-in member in the wall of a glass'cathode-ray tube constructed of x-radiation shielding glass.

It has recently been discovered that under certain conditions cathode-ray tubes, particularly those used in color television, can be the source of x-radiation; and, while no definite proof exists that the quantity of radiation produced is harmful, it has become a source of concern.

In efforts to alleviate this problem, glass manufacturers have developed materials which substantially reduce the emission of x-radiation. One such material which has been used for this purpose in the past is a glass with a high lead content. Recent improvements have utilized a strontium bearing glass.. When these glasses were employed in the manufacture of cathoderay tube envelopes however, it was discovered that some xradiation was still leaking. The source of this leakage was found to be the anode terminal connector, more commonly 7 called a second anode button. The second anode button is a hollow, electrically conductive member that is sealed into a wall of the cathode-ray tube envelope. The bottom surface of the button communicates with the interior of the envelope and the top of the button, which is provided with a flange which defines a reduced area aperture, communicates with the exterior surface. In a finished tube the interior surface of the envelope is provided with an electrically conductive coating, such as Aquadag and the bottom of the button is in electrical contact therewith. The high voltage necessary for tube operation is applied to this anode coating from the exterior of the tube by means of a terminal clip which engages the second anode button.

As regards the leakage of x-radiation, it was found to be emanating more specifically from the reduced area aperture defined by the circumscribed flange at the top of the second anode button.

OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, an object of this invention to reduce or substantially eliminate this undesired radiation.

It is a further object of the invention to provide an anode button capable of performing thisdesired elimination.

These objects are achieved in one aspect of the invention by the provision of an anode button for use a a sealed-in member in a wall of a cathode-ray tube which comprises a substantially hollow button having an aperture in the top surface. An xradiation shield is affixed therein comprising a bottom having an upstanding circumferential wall thereabout and an open top. The area of the top is larger than the area of the aperture and the height of the wall is just less than'tlie interior height of the button.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is an elevational sectional view of one embodiment of the invention; and

FIG. 2 is a similar view of an alternate embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure arid appended claims in connection with the above-described drawings. 1

Referring now to the drawings with greater particularity, there is shown a one-piece anode button 10 of a type known in the art. The button 10 is sealed in the glass wall 12 of a cathode-ray tube envelope, the wall being shown as a fragmentary portion only. The glass is of a type that is substantially x-radiation impervious. The button 10 comprises a substantially frustoconical body 14 having a circumferential sidewall 16 and substantially parallel spaced-apart top and bottom portions 18 36 20 respectively, which are contiguous with the sidewall 16 32 form a 45 unit. One surface 21 of the bottom 20 of the button 10 is in electrical contact with a conductive coating 23 on the interior of the envelope. The button has a longitudinal axis 22 which passes substantially through the center of top portion 18 and bottom portion 20. The top 18 has a reduced area aperture 24 therein, substantially symmetrically located with respect to axis 22 and which is geometrically configures; in this instance circular and having a diameter A. Positioned within hollow body 14 is a radiation shield 25 which has a bottom 26 with an upstanding circumferential wall 28 therearound.

The shield has an open top 30 which has a diameter B which is greater than that of aperture A. The shield is not fastened within the body and is free to move, and to enhance this effect the height of the wall 28 is less than the interior height of the button 10. This construction provides excellent radiation promotion from all directions.

It is to be noted that while apertures 24 and 30 are in this case circular, other configurations can be used; e.g., square, rectangular, hexagonal, etc.

The button material has a coefficient of thermal expansion substantially matching that of the glass and a readily available material is one known as 04 alloy; an alloy of nickel, chromium and iron which is available from Sylvania Electric Products Inc. The shield is preferably made from the same material and is .0l2 inches thick or greater. Alternatively, the shield can be made from any other material equally impervious to x-radiation.

Referring now to FIG. 2, there is shown an anode button 32 of two-piece construction. The button 32 is similar in all respects to button 10 except that the geometrically configured aperture 34 is formed in an insert 36 which has a formed peripheral section 38 which contacts the interior surface of button 32 at the widest point thereof. A formed circumferential flange 40 holds the apertured insert 36 in position. This particular structure has greater mechanical strength than the one-piece button and for this reason is occasionally preferred thereover. As with button 10, the button 32 is provided with a radiation shield 42 of similar size and shape and axial location with respect to aperture 34.

These buttons provide many advantages over the prior art. They provide adequate shielding to keep leakage of x-radiation below the minimum exposure recommended (.5 mr./hr. at .3 ma. and 35 KV); and the floating, free to move shield allows easy exit of any cleaning or rinsing materials that have been used during the tube manufacture.

While there have been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

We claim:

I. An anode button for use as a sealed-in member in the wall of a cathode-ray tube capable of generating x-radiation comprising: a substantially frustoconical body having a circumferential sidewall and substantially parallel spaced-apart top and bottom portions contiguous with said sidewall to form a hollow unit; said button having a longitudinal axis passing substantially through the center of said top and bottom portions and said top portion having therein a geometrically configured aperture having a given area; said aperture being substantially symmetrically located with respect to said axis, and a radiation shield positioned within said body; said shield comprising a bottom having a circumferential sidewall therearound and an open top, the area of said top being greater than the area of said aperture.

2. The invention of claim 1 wherein said shield is loosely fitted within said body and is free to move small distances.

3, A cathode-ray tube envelope comprised of an electrically insulating'material substantially impervious to the passage of x-radiation, said envelope having sealed in a wall thereof a hollow electrically conductive button having a bottom portion communicating with the interior of said envelope and a top portion communicating with the exterior of said envelope, said top and bottom portions being joined by a circumferential W105" UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,600,620 Dated August 17, 1971 Inventofls) Edward C. Slick and Floyd H. West It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 5 of the specification "36" should read--and--.

Column 2, line 6 of the spec. "32" should readto-n- Column 2 line 6 of the spec. "45" should read--hollow--.

Column line 29 of the spec. "04" should read--#4--.

Signed and sealed this 29th day of February 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

1. An anode button for use as a sealed-in member in the wall of a cathode-ray tube capable of generating x-radiation comprising: a substantially frustoconical body having a circumferential sidewall and substantially parallel spaced-apart top and bottom portions contiguous with said sidewall to form a hollow unit; said button having a longitudinal axis passing substantially through the center of said top and bottom portions and said top portion having therein a geometrically configured aperture having a given area; said aperture being substantially symmetrically located with respect to said axis, and a radiation shield positioned within said body; said shield comprising a bottom having a circumferential sidewall therearound and an open top, the area of said top being greater than the area of said aperture.
 2. The invention of claim 1 wherein said shield is loosely fitted within said body and is free to move small distances.
 3. A cathode-ray tube envelope comprised of an electrically insulating material substantially impervious to the passage of x-radiation, said envelope having sealed in a wall thereof a hollow electrically conductive button having a bottom portion communicating with the interior of said envelope and a top portion communicating with the exterior of said envelope, said top and bottom portions being joined by a circumferential sidewall and said top portion having therein a geometrically configured aperture having a given area; and a radiation shield positioned within said body; said shield comprising a bottom having a circumferential sidewall therearound and an open top, the area of said top being greater than the area of said aperture. 